How to use SSS texture in Blender?
If the texture is a black and white image, chances are that it is supposed to drive the Subsurface Amount. Simply connect the Color Output to the Subsurface Input in the Principled Shader. If the image is colored, connect it to the Subsurface Color input to drive the Color of subsurface.
Here is an image of how to connect the nodes (assuming you have a black and white texture):
The top setup is basic, and the bottom setup gives you more control over the amount of subsurface by adjusting the ColorRamp.